Automotive engines are frequently equipped with a pump which supplies air to the engine exhaust system to support oxidation of exhaust gas constituents. To assure adequate pump life, it is important that dust and water be filtered from the air flowing into the pump.
One pump used heretofore for that purpose is illustrated in U.S. Pat. No. 3,370,785 issued Feb. 27, 1968 in the name of F. L. J. Rehfeld and J. E. Pasek. That pump employed a rotating filter element which centrifuged foreign material out of the air flowing into the pump.